Between 01.38 and 01.41 hours on 25 Aug 1942, U-605 fired four single bow and one stern torpedoes from a distance of about 4000 meters at the outermost starboard column of convoy ONS-122 southeast of Cape Farewell. Detonations on three ships were observed after 5 to 7 minutes and one ship was seen to caught fire and sink within a minute after breaking in two. Schütze claimed one ship sunk and two others damaged. In fact, the Katvaldis in station #92 and Sheaf Mount in station #94 were sunk in this attack.

The Sheaf Mount (Master Ralph Sydney De-Gruchy) was hit on the starboard side in the engine room and immediately settled by the stern. The crew began to abandon ship, but before the lifeboats could be launch the vessel broke in two after a heavy explosion, possibly hit by another torpedo from U-605. She caught fire and sank within two minutes, dragging all lifeboats down with her. The survivors found themselves in the water and clung to debris and wreckage until being picked up within 2.5 hours by the Stockport (Master Thomas Ernest Fea, OBE) in thick fog, greatly helped by the red lights and whistles carried on the lifebelts. The master, 26 crew members and three gunners were lost. 14 crew members and seven gunners (the ship was armed with one 4in, one 12pdr, two 20mm AA guns and two twin machine guns) were picked up, but one badly injured crewman later died aboard and was buried at sea. The survivors were landed at Halifax on 1 September.